Epidemiology is a branch of science that deals with the incidence, distribution and control of disease in a population. It is a core public health science. Epidemiologists monitor health trends and statistics to identify groups of people who are affected by various diseases. In addition, epidemiologists investigate cases of disease to determine the source, modes of transmission, and risk factors for disease. This information is then used to implement control measures to prevent the spread of disease.

The Epidemiology Program conducts mandated surveillance and reporting of more than 75 notifiable diseases and medical conditions. In addition, this program conducts disease investigations and coordinates appropriate prophylaxis and interventions in many of those diseases as well as any cluster of illnesses in order to prevent secondary cases and outbreaks. Epidemiology provides consultation and education on these diseases and works closely with County, City and State government agencies to enable appropriate public health follow-up for patients, contacts and medical care providers.